Rotary hydraulic machine

Description

[0001] The present invention is directed to rotary hydraulic machines according to the preamble of claim 1. Such machines of the sliding-vane type are capable of functioning as hydraulic pumps or motors.

[0002] Rotary hydraulic machines of the subject type generally include a housing, a rotor mounted for rotation within the housing and having a plurality of radially extending peripheral slots, and a plurality of vanes individually slidably mounted in the slots. A cam ring surrounds the rotor and has a radially inwardly directed surface forming a vane track and one or more fluid pressure cavities between the cam surface and the rotor. Inlet and outlet passages feed hydraulic fluid to and from the cavities.

[0003] It is necessary in operation of machines of this character that the rotor vanes slidably engage the opposing cam ring surface. During operation, the vanes are urged outwardly against the cam ring surface by centrifugal force. However, there are many conditions existing and forces created tending to prevent the vanes from acting freely as cam ring surface followers, and also causing the vanes to collapse or retract from the vane track, such as both mechanical and viscous friction, bearing loads of the vanes against the track or between the vane and rotor, and differential pressures creating unfavorable resultant forces acting on the extreme inner or outer edges of the vanes. Further, upon initial operation of the machine, it is undesirable to permit the vanes to be spaced from the opposing cam ring surface, both because of pressure loss as fluid freely flows over vanes, and also because centrifugal forces can cause the vanes to be damaged by impact against the cam ring surface.

[0004] To overcome the afore-mentioned problems, it has heretofore been proposed to form chambers in the rotor beneath the vane slots. Springs are positioned within these rotor chambers and/or fluid is fed under pressure to the rotor chambers for urging the vanes radially outwardly against the cam ring surface. The vane springs, where employed, exhibit varying spring rate both among individual springs and over the operating life of a given spring, possess a limited operating life, and frictionally wear against the opposing edges of the vanes. Provision of undervane fluid pressure, either intermittent or continuous, usually requires the use of valves for feeding the fluid to the undervane chambers prior to the primary machine cavities, and also does not overcome the problem of vane impact against the cam ring surface except where combined with the vane springs. So-called inner vane machines have addressed, but not entirely overcome the problems in question.

[0005] In a further proposal (GB-A-1,140,213) to overcome the afore-mentioned problems, cam means are provided within the housing which limit the travel of the vanes inwardly. The cams however have profiled surfaces which are equidistant from the profiled surfaces of the vane track surface only in the section situated between the port openings used for the delivery and draining of the working fluid. In the other sections, the cam means show flat surfaces so that the separation between the vane track surface and the cam ring surface is non-uniform. Therefore, the clearance between the outer ends of the vanes and the vane track surface is non-uniform so that two distinct disadvantages will follow. First, in the event of fluctuation or loss of fluid pressure, even minimum sealing is precluded. Second, when the machine is initially started, the vanes travel for a substantial distance and gather momentum before impact against the vane track surface. This tends to damage the vane tips and the vane track surface.

[0006] The problem to be solved by the present invention is to overcome the deficiencies mentioned above.

[0007] The solution of the problem is in the combination of the features of claim 1. Further claims 2 through 5 show further developments of the present invention.

[0008] According to the present invention, a rotary hydraulic machine is provided that includes facility ensuring that the vanes are continually positioned adjacent to the cam ring surface. Furthermore, frictional wear can be reduced, and the machine is less expensive to manufacturer than are prior art machines of similar type.

[0009] The machine of the present invention can also be used for dividing a single input flow of hydraulic fluid into two or more output flows at a predetermined flow ratio. Prior art devices for this purpose have involved relatively complex and expensive specialised structures.

[0010] The present invention contemplates a vane-type rotary hydraulic machine that comprises a housing, a rotor mounted within the housing and having a plurality of radially extending peripheral slots, and a plurality of vanes individually slidably mounted in the rotor slots. A cam ring within the housing surrounds the rotor and has a radially inwardly directed surface forming a track for sliding engagement with the vanes, and at least one fluid pressure cavity between the cam ring surface and the rotor. Fluid inlet and outlet passages in the housing are coupled to the pressure cavity.

[0011] In accordance with a first aspect of the present invention that is useful in pumps, motors and other vane-type machines of the subject character, a cam mechanism is mounted with the housing in fixed position with respect to the cam ring and has a surface for engaging the radially inner edges of the vanes to position the radially outer vane edges adjacent to the cam ring surface. In the preferred embodiment of the invention, such cam mechanism takes the form of a pair of cam plates having continuous radially orientated surfaces contoured substantially identically to the cam ring surface and spaced radially inwardly therefrom by a distance corresponding to, and preferably slightly greater than, the radial dimension of the rotor vanes. The cam plates are carried by the housing and positioned in cylindrical pockets formed in the opposed axially outwardly facing surfaces of the rotor. Thus, the cam plates uniformly engage the inner edges of the vanes at axially spaced positions. Further, in the preferred embodiment of the invention, fluid pressure chambers are formed in the rotor beneath the vane slots, so that fluid pressure urges the vanes against the cam ring surface during normal operation while lifting the vanes from the cam plate surfaces, thereby eliminating frictional contact and wear between the vanes and the cam plates surfaces.

[0012] In accordances with a second aspect of the present invention, the rotor is mounted for free rotation within the housing on a stub shaft completely enclosed by the housing. The rotor and cam ring form at least two fluid pressure cavities, preferably two cavities radially symmetrically positioned with respect to the stub shaft. The machine thus forms a vane-type flow divider for dividing an input flow of hydraulic fluid under pressure into two output flows at a predetermined flow ratio, specifically at a 1:1 ratio in the preferred embodiment of the invention. Pressure drop between the inlet and outlets is greatly reduced as compared with prior art devices for a similar purpose.

Brief Description of the Drawings

[0013] The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a schematic diagram of a vane-type hydraulic fluid flow divider in accordance with a presently preferred embodiment of the invention;

FIG. 2 is an end elevational view of a flow divider in accordance with the invention;

FIG. 3 is a sectional view taken substantially along the line 3-3 in FIG. 2; and

FIG. 4 is a sectional view taken substantially along the line 4-4 in FIG. 3

Detailed Description of Preferred Embodiment

[0014] FIG. 1 schematically illustrates a balanced dual-lobe vane-type rotary hydraulic machine 10 as comprising a rotor 12 rotatable mounted on a shaft 14. Rotor 12 has a circular periphery and a circumferential array of radially directed slots 16 in which a corresponding plurality of vanes 18 are radially slidably disposed. A cam ring 20 radially surrounds rotor 12, and has a radially inwardly directed cam ring surface 22 that cooperates with rotor 12 and vanes 18 to form a pair of diametrically opposed fluid cavities 24, 26. Hydraulic fluid is fed from an inlet 28 to a pair of inlet ports 30, 32 in communication with cavities 24, 26, and the respective cavities also communicate through outlet ports 34, 36 and cross-over passages 35, 37 with the respective fluid outlets 38, 40. A chamber 44 is formed in rotor 12 beneath each slot 16 and communicates with ports 30, 32 so that hydraulic fluid pressure urges vanes 18 radially outwardly against surface 22 of cam ring 20. To the extent thus far described (with the exception of separate outlets 38, 40), machine 10 is of generally conventional construction, and can operate either as a pump, in which rotor 12 is driven in the direction 42 by shaft 14 to pump fluid from low pressure inlet 28 to high pressure outlets 38, 40, or as a motor in which flow of fluid from high pressure inlet 28 to low pressure outlets 38, 40 drives rotor 12 and shaft 14 in the direction 42.

[0015] In accordance with a first important aspect of the present invention, a cam plate 46 (FIG. 1) is mounted in fixed position relative to cam ring 20 surrounding shaft 14. Cam plate 46 has a radially outwardly directed edge surface 48 that engages the radially inner edges of vanes 18 and is substantially identical in contour, yet reduced in size to the opposing surface 22 of cam ring 20. Cam plate surface 48 is spaced from cam ring surface 22 by a distance slightly greater than the radial dimension of vanes 18. Thus, cam plate 46 positions vanes 18 radially adjacent to surface 22 of cam ring 20 at all positions of rotor 12. The vanes are thus automatically positioned to substantially seal cavities 24, 26 upon initial operation of machine 10, and minimize travel of vanes 18 into radial impact with cam ring surface 22 as fluid pressure is supplied to chambers 44. However, when fluid pressure is applied to chambers 44, such fluid pressure urges vanes 18 against cam ring surface 22 so that the vane inner edges are spaced from surface 48 of cam plate 46, thereby reducing sliding friction and wear between the vanes and the cam plate surface. In accordances with a second important aspect of the present invention, rotor 12 is not rotatably coupled to shaft 14, but rather freely rotates with respect thereto, while shaft 14 is completely enclosed within the surrounding housing. Thus, machine 10 forms a flow divider for dividing input fluid flow at inlet 28 into separate output flows at outlets 38, 40.

[0016] FIGS. 2-4 illustrate a presently preferred embodiment of rotary hydraulic fluid flow divider 10. Reference numerals in FIGS. 2-4 identical to those employed in the schematic diagram of FIG. 1 indicate corresponding elements. Rotor 12 is freely rotatably mounted on stub shaft 14, which is affixed by a bolt 50 to the cover plate 52 of machine housing 54. A washer 56 cooperates with bolt 50 to capture a backup plate 58, with cam ring 20 being sandwiched between backup plate 58 and cover plate 52 to form the rotor cavity. Backup plate 58 and cam ring 20 are surrounded by a cup-shaped casing 60 that is affixed by bolts 62 to cover plate 52 to complete housing 54. Separate annular cavities 61, 63 are formed between casing 60 and plate 58 to feed the respective output flows to outlets 38, 40. Cover plate 52 and backup plate 58 have axially opposed flat surfaces 53, 59 that face opposing axially outwardly orientated flat surfaces 13, 15 of rotor 12. A cam plate 46 is mounted on the rotor-facing surface of each plate 52, 58 and is held thereon by the pins 64. Each cam plate is thus positioned in a substantially cylindrical pocket 74 (Fig. 4) in the opposing rotor surface, with the outer edge surface 48 of each cam plate 48 engaging the opposing inner edges of vanes 18 as previously described.

[0017] Inlet 28 (Figs. 1 and 2) communicates with ports 30, 32 as previously described, and thence through a passage 66 (Fig. 3) to a sealed cavity 68 in backup plate 58. A passage 70 extends from cavity 68 to an annular channel 72 on the rotor-opposing face of backup plate 68 to form a hydraulic clamp mechanism to hold backup plate 58 to cam ring 22 to end cover 52. Channel 72 is at a radius from the axis of rotation of rotor 12 corresponding to the radial position of fluid chambers 44, and thus feeds fluid at substantially inlet pressure to rotor chambers 44 for urging vanes 18 radially outwardly against cam ring surface 22.

[0018] Instead of a dual-lobe vane-type rotary hydraulic machine 10 which includes two fluid travel cavities 24, 26, also multi-lobe machines can be provided to make three, four etc. fluid travel cavities. In such cases, inlet and outlet passages are multiplied in accordance with the number of the lobes. The input flow then is divided in three or four etc. output flows. The cavities normally are equal in size, then also the flows are equal in rate. Yet it is also possible to make the volumes of the cavities different so as to provide a desired predetermined flow ratio between the output flows.

Claims

1. A rotary hydraulic machine comprising:
a housing (54),
a rotor (12) mounted for rotation within said housing, said rotor having a plurality of radially extending peripheral slots (16), each ending in an undervane chamber (44),
a plurality of vanes (18) individually slidably mounted in said slots (16) and being of a predetermined radial dimension,
a cam ring (20) within said housing (54) surrounding said rotor (12) and having a radially inwardly directed vane track surface (22)
at least one fluid travel cavity (24, 26) between said vane track surface (22) and said rotor (12),
fluid inlet (30, 32) and outlet (34, 36) means in said housing (54) hydraulically connected to said at least one cavity (24, 26),
cam means (46) mounted within said housing in fixed position within said cam ring (20), said cam means (46) having a radially outwardly oriented cam surface (48) which becomes effective during non-operation of the machine or in the event of fluctuation or loss of fluid pressure to engage the inner ends of said vanes (18) and to position the radially outer ends adjacent to, but spaced from said cam ring surface (22), said housing (54) including means (70, 72) for feeding fluid under pressure to said undervane chambers (44) so as to lift said vanes (18) from said cam surface (48) and urge the outer ends of said vanes (18) against said vane track surface (22) characterized in that
said cam surface (48) has a continuous contour of substantially the same form, yet reduced in size to the contour of said vane track surface (22) so that said cam surface (48) is spaced from said vane track surface (22) by a substantially- uniform distance that is slightly greater than said radial dimension of said vanes (18).

2. The machine (10) set forth in claim 1
wherein said rotor (2) has a substantially flat side face and a pocket formed in said side face,
wherein said housing includes means forming a substantially flat face opposed to said rotor side face, and
wherein said cam means (46) comprise a flat cam plate affixed to said housing (54) and positioned in said pocket.

3. The machine set forth in claim 1
wherein said rotor (12) has a pair of substantially flat side faces (13, 15) each having a substantially circular axially outwardly opening pocket (74) formed therein,
wherein said housing (54) includes means forming substantially flat faces (53, 59) opposed to said side faces (13, 15) and
wherein said cam means (46) comprises a pair of substantially identical cam plates affixed to said housing (54) and positioned in respective ones of said pockets (74) for balanced engagement with said radially inner ends of said vanes (18).

4. A machine as set forth in any of claims 1 to 3
for dividing an input flow of hydraulic fluid into at least two output flows at a predetermined flow ratio,
wherein said rotor (12) is mounted for free rotation within said housing (54) on a stub shaft (14) completely enclosed by said housing (54), said machine comprising at least two fluid travel cavities (24, 26) between said vane track surface (22) and said rotor (12), means (28, 30, 32) in said housing (54) for feeding said input flow of hydraulic fluid under pressure to said cavities (24, 26), and means (34, 36, 38, 40) in said housing for providing said at least two output flows from said cavities (24, 26).

5. The machine set forth in claim 4
wherein said rotor (12) and cam ring (20) are constructed and arranged to form two (24, 26) of said cavities radially symmetrically positioned with respect to said stub shaft (14).

Ansprüche

1. Hydraulische Drehkolbenmaschine mit folgenden Merkmalen:
ein Gehäuse (54);
ein Rotor (12) ist zur Drehung innerhalb des Gehäuses gelagert und weist eine Mehrzahl von radial sich erstreckenden peripheren Schlitzen (16) auf, die jeweils in einer Uterflügelkammer (44) enden;
eine Mehrzahl von Flügel (18) sind individuell in den Schlitzen (16) verschieblich gelagert und weisen eine vorbestimmte radiale Dimension auf;
ein Nockenring (20) innerhalb des Gehäuses (54) umgibt den Rotor (12) und weist eine radial nach innen gerichtete Flügelbahnoberfläche (22) auf;
mindestens ein Fluidverschiebungsraum (24, 26) ist zwischen der Flügelbahnoberfläche (22) und dem Rotor (12) vorgesehen;
Fluideinlaß- (30, 32) und Auslaß- (34, 36) Einrichtungen sind in dem Gehäuse (54) hydraulisch mit mindestens dem einen Raum (24, 26) verbunden;
eine Nockeneinrichtung (46) ist innerhalb des Gehäuses in fester Stellung innerhalb des Nockenrings (20) montiert und weist eine radial nach außen gerichtete Nockenoberfläche (48) auf, die während des Nichtbetriebes der Maschine oder im Fall von Fluktuation oder Druckverlust wirksam wird, um an den inneren Enden der Flügel (18) anzugreifen und die äußeren radialen Enden benachbart, jedoch mit einem bestimmten Abstand von der Nockenringoberfläche (22) zu positionieren; das Gehäuse (54) weist eine Einrichtung (70, 72) zur Zuführung von unter Druck stehendem Fluid zu den Unterflügelkammern (44) auf, um die Flügel (18) von der Nockenoberfläche (48) anzuheben und die äußeren Enden der Flügel (18) gegen die Flügelbahnoberfläche (22) zu drängen, dadurch gekennzeichnet,
daß die Nockenoberfläche (48) eine kontinuierliche Kontur mit im wesentlichen der gleichen Form wie die Kontur der Flügelbahnoberfläche (22), jedoch reduziert in ihrer Größe, aufweist, so daß die Nockenoberfläche (48) von der Flügelbahnoberfläche (22) um einen im wesentlichen gleichförmigen Abstand augeordnet ist, der ein wenig größer als die radial Abmessung der Flügen (18) ist.

2. Maschine (10) nach Anspruch 1,
dadurch gekennzeichnet, daß der Rotor (2) eine im wesentlichen ebene Seitenfläche und eine in der Seitenfläche geformte Tasche aufweist,
daß das Gehäuse eine Einrichtung zur Bildung einer im wesentlichen flachen Seite gegenüber der Rotorseitenfläche aufweist und daß die Nockeneinrichtung (46) eine flache Nockenplatte umfaßt, die an dem Gehäuse (54) befestigt und in der Tasche gelegen ist.

3. Maschine nach Anspruch 1,
dadurch gekennzeichnet, daß der Rotor (12) zwei im wesentlichen ebene Seitenflächen (13, 15) aufweist, die jeweils im wesentlichen kreisförmige, axial nach außen sich öffnende und darin eingeformte Taschen (54) aufweisen,
daß das Gehäuse (54) eine Einrichtung zur Bildung von flachen Seiten (53, 59) aufweist, die diesen Seitenflächen (13, 15) gegenüberstehen und
daß die Nockeneinrichtung (46) zwei im wesentlichen identische Platten aufweist, die an dem Gehäuse (54) befestigt sind und jeweils in einer der Taschen (74) zum hinsichtlich Druck ausgeglichenen Eingriff an den radial inneren Enden der Flügel (18) gelegen sind.

4. Maschine nach einem der Ansprüche 1 bis 3, zur Aufteilung einem Eingangsstroms von hydraulischem Fluid in mindestens zwei Ausgangsströme bei vorbestimmtem Stromverhältnis, dadurch gekennzeichnet,
daß der Rotor (12) zur freien Drehung innerhalb des Gehäuses (54) auf einer Stummelachse (14) gelagert ist, die vollständig von dem Gehäuse (54) umschlossen ist, daß die Maschine mindestens zwei Stromverschiebungsräume (24, 26) zwischen der Flügelbahnoberfläche (22) und dem Rotor (12) aufweist, daß eine Einrichtung (28, 30, 32) in dem Gehäuse (54) zur Förderung des Eingangsstromes an unter Druck stehendem hydraulischen Fluid zu den Räumen (24, 26) und eine Einrichtung (34, 36, 38, 40) in dem Gehäuse zur Lieferung mindestens zweier Auslaßströme aus den Räumen (24, 26) vorgesehen sind.

5. Maschine nach Anspruch 4, dadurch gekennzeichnet,
daß der Rotor (12) und der Nockenring (20) so konstruiert und angeordnet sind, daß zwei (24, 26) der Räume radial symmetrisch mit Bezug auf die Stummelachse (14) angeordnet sind.

Revendications

1. Machine hydraulique rotative comprenant
un carter (54),
un rotor (12) monté rotatif à l'intérieur dudit carter, ledit rotor comportant de multiples fentes (16) orientées radialement à la périphérie et dont chacune aboutit dans une chambre (44) sous palette,
de multiple palettes (18) montées coulissantes individuellement dans lesdites fentes (16) et ayant une dimension radiale prédéterminée,
une came en anneau (20) disposée à l'intérieur dudit carter (54), entourant ledit rotor (12) et présentant une surface (22) de glissement des palettes qui est orientée radialement vers l'intérieur,
au moins une cavité (24, 26) de passage de fluide située entre ladite surface (22) de glissement des palettes et ledit rotor (12),
des moyens d'admission (30, 32) et de sortie (34, 36) du fluide réalisés dans ledit carter (54) et communiquant hydrauliquement avec ladite au moins une cavité (24, 26),
un moyen à profil de came (46) monté à dans ledit carter en position fixe à l'intérieur de ladite came en anneau (20), ledit moyen à profil de came (46) comportant une surface de came (48) orientée radialement vers l'extérieur en entrant en action, en l'absence de fonctionnement de la machine ou en cas de fluctuation ou de chute de la pression de fluide, en s'appliquant contre l'extrémité intérieure desdites palettes (18) et en positionnant l'extrémité radialement extérieure de ces dernières à proximité de, mais à distance de ladite surface (22) de la came en anneau, ledit carter (54) étant équipé de moyens (70, 72) pour alimenter en fluide sous pression lesdites chambres (44) sous palette de manière à soulever lesdites palettes (18) de ladite surface de came (48) et à plaquer l'extrémité extérieure desdites palettes (18) contre ladite surface de glissement (22) des palettes,
caractérisée en ce que ladite surface de came (48) a un contour continu ayant sensiblement la même forme, toutefois une dimension plus petite que le contour de ladite surface (22) de glissement des palettes, de telle manière que ladite surface de came (48) soit placée par rapport à ladite surface (22) de glissement des palettes à une distance sensiblement constante qui est légèrement supérieure à ladite dimension radiale desdites palettes (18).

2. Machine (10) selon la revendication 1,
dans laquelle ledit rotor (2) présente une surface latérale sensiblement plane et une poche formée dans ladite surface latérale,
ledit carter comprenant des moyens formant une surface sensiblement plane qui est opposée à ladite surface latérale du rotor et ledit moyen à profil de came (46) consistant en une plaque plane à profil de came qui est fixée audit carter (54) et placée dans ladite poche.

3. Machine selon la revendication 1,
dans laquelle ledit rotor (12) comporte deux surfaces latérales sensiblement planes (13, 15) dans chacune desquelles est formée une poche sensiblement circulaire (74) s'ouvrant axialement vers l'extérieur,
ledit carter (54) comprenant des moyens formant des surfaces sensiblement planes (53, 59) opposées auxdites surfaces latérales (13, 15) et
ledit moyen à profil de came (46) consistant en deux plaques sensiblement identiques à profil de came qui sont fixées audit carter (54) et placées chacune dans l'une desdites poches (74) de façon qu'elles s'appliquent de manière équilibrée contre ladite extrémité radialement interne desdites palettes (18).

4. Machine selon l'une quelconque des revendication 1 à 3,
destinée à diviser une admission d'un flux de fluide hydraulique en au moins deux flux de sortie suivant un rapport prédéterminé de débits, machine dans laquelle
ledit rotor (12) est monté de manière à tourner librement à l'intérieur dudit carter (54) sur un bout d'arbre (14) entièrement enfermé dans ledit carter (54), ladite machine comprenant au moins deux cavités (24, 26) de passage de fluide qui sont situées entre ladite surface (22) de glissement des palettes et ledit rotor (12), des moyens (28, 30, 32) réalisés dans ledit carter (54) et destinés à diriger ledit flux d'admission de fluide hydraulique sous pression dans lesdites cavités (24, 26) et des moyens (34, 36, 38, 40) étant réalisés dans ledit carter pour produire lesdits au moins deux flux de sortie desdites cavités (24, 26).

5. Machine selon la revendication 4, dans laquelle
ledit rotor (12) et ladite came en anneau (20) sont conformés et disposés de manière à former deux (24, 26) desdites cavités de façon qu'elles soient placées radialement de manière symétrique par rapport audit bout d'arbre.

Drawing